The Dude, His Dudeness, El Duderino(if you're not into the whole brevity thing). Also a member of the Seattle Seven and author of the Port Heron Statement (the original version, not the compromised second draft).

You're Mr. Lebowski, I'm the Dude. So thats what you call me ok. Either that or His Dudeness or El Duderino.
You got the wrong guy...i'm not lebowski...does it look like i'm fucking married, the toilet seat is up man.